Most of the calories humans consume come directly or indirectly from seeds, and the nutritional properties of seeds are major contributors to human health. Seed maturation includes all the processes that lead to the accumulation of edible storage products and desiccation. There is no clear understanding on how the timing of the developmental switch that leads to seed maturation is controlled. The long-term goal of this project is to understand the genetic mechanisms that regulate seed maturation, in particular the pathways that prevent the maturation genes to be expressed early in seed development and after germination. Understanding how maturation is regulated will increase our understanding of developmental transcriptional switches in general. It may also help manipulate the nutritional content of crop seeds. This proposal focuses on two transcription factors, ASIL1 and ASIL2 (the ASIL genes), which are good candidates for repressors of maturation in the model plant Arabidopsis thaliana. Because the seed maturation programs appear to be conserved among flowering plants, the findings could be applied to crop plants. This proposal aims to investigate two separate aspect of the biology of the ASIL genes. The first aim is to study the roles of these genes during development, by analyzing which genes and pathways they regulate. By comparing their actions in two compartments of the seed (embryo and endosperm) and in the young seedling, the redundancy (or lack thereof) of their functions can be evaluated. This will help establish whether the same set of genes regulate maturation during seed development and after germination. The second aim is to understand the transcriptional regulation of the AISL genes, to see whether and which discreet regions of their promoters direct expression at different times and tissue types. This information will enable the future search for upstream regulators. The first aim will be accomplished by collecting tissue at the appropriate stages (using Laser Capture MicroDissection in the case of the embryo and endosperm), isolating RNA, quantifying the abundance of transcripts using RNAseq, and comparing the different tissue types and stages using the appropriate bioinformatic analysis tools. The second aim will be addressed by generating transcriptional and translational fusions of selected segments of the promoters to the reporter genes GUS and GFP, and studying their expression in transgenic plants.